#include<stdio.h>
#include<conio.h>
#include<math.h>
int main(){
	float s,r;
	printf("nhap vao ban kinh r: ");
	scanf("%f",&r);
	printf("dien tich cua hinh tron can tinh la: s= %0.2f",s=M_PI*pow(r,2));
 getch();
}
